Current technologies of some wet processes for a wafer require that the wafer be etched or plated only on one side and perhaps only in the device region of that one side. That is, for technical reasons, etching or plating of the edge of the wafer is to be avoided. Some of these processes involve generic isotropic wet etching, anisotropic wet etching, e.g., KOH etching, plating, and various other wet operations.
In some applications the wafer fixture or fixture for holding the wafer is made of PEEK, and in other applications it may be made of stainless steel or titanium. The choice of material is based on the process requirements and upon manufacturing requirements of the fixture and costs. Some fixtures may be used for just one step and other fixtures may have to run more than one wet process. So, material choices can be complicated. In addition to chemical requirements, there may be thermal requirements of the process, and thus the fixture and its materials.
Heretofore, the preferred fixtures have been made in accordance with the prior art fixture of FIG. 1. The fixture 100 of FIG. 1 has a backing plate 110 and circular top frame 120. Both parts contain O-rings 130. A wafer is placed into fixture 100 and the wafer is clamped between the O-rings 130 by use of screws 140. The use of screws 140, however, makes for a tedious task of assembling the fixture 100 with the wafer in position, especially for multiple wafer baths. With the prior fixtures, the number of screws is limited in order to keep the task of assembly to a minimum. Therefore, the number of pressure points around the wafer is limited to the points where the screws are located, and the pressure on the wafer may be localized to the locations of the screws. That is, the pressure may not be equalized around the outer edge of the wafer. Additionally, there is a risk of losing the screws and dropping the screws onto the wafer surface, which is very undesirable.
Thus, there is a need in the art for a wafer fixture without the complications presented by prior wafer fixtures. There is a need in the art for an improved wafer fixture that is easier to use and assemble, has fewer total parts needed for assembly, and/or eliminates the risk of dropping a screw onto the wafer surface. Additionally, there is a need in the art for a wafer fixture using an internal locking and docking mechanism for securing a wafer, which eliminates the use of several screws to secure the wafer. There is a further need in the art for a wafer fixture wherein the number of pressure points retaining a wafer may be increased without increasing the complexity of or amount of time needed for assembling the wafer fixture.